New Revised Standard Version
Did the baptism of John come from heaven, or was it of human origin?” And they argued with one another, “If we say, ‘From heaven,’ he will say to us, ‘Why then did you not believe him?’

Contemporary English Version
Who gave John the right to baptize? Was it God in heaven or merely some human being?" They thought it over and said to each other, "We can't say God gave John this right. Jesus will ask us why we didn't believe John.

New American Bible
Where was John’s baptism from? Was it of heavenly or of human origin?” They discussed this among themselves and said, “If we say ‘Of heavenly origin,’ he will say to us, ‘Then why did you not believe him?’

Douay-Rheims Bible
The baptism of John, whence was it? From heaven or from men? But they thought within themselves, saying:

The baptism of John, whence was it? From heaven or from men? But they thought within themselves, saying:

baptism.

Matthew 3:1 And in those days cometh John the Baptist preaching in the desert of Judea.

*etc:

Matthew 11:7-15 And when they went their way, Jesus began to say to the multitudes concerning John: What went you out into the desert to see? a reed shaken with the wind? . . .

Matthew 17:12,13 But I say to you, that Elias is already come, and they knew him not, But have done unto him whatsoever they had a mind. So also the Son of man shall suffer from them. . . .

Mark 1:1-11 The beginning of the gospel of Jesus Christ, the Son of God. . . .

Mark 11:27-33 And they come again to Jerusalem. And when he was walking in the temple, there come to him the chief priests and the scribes and the ancients. . . .

Luke 1:11-17,67-80 And there appeared to him an angel of the Lord, standing on the right side of the altar of incense. . . .

Luke 3:2-20 Under the high priests Anna and Caiphas: the word of the Lord was made unto John, the son of Zachary, in the desert. . . .

Luke 7:28-35 For I say to you: Amongst those that are born of men, there is not a greater prophet than John the Baptist. But he that is the lesser in the kingdom of God is greater than he. . . .

John 1:6,15,25-34 There was a man sent from God, whose name was John. . . .

John 3:26-36 And they came to John and said to him: Rabbi, he that was with thee beyond the Jordan, to whom thou gavest testimony: behold, he baptizeth and all men come to him. . . .

Why.

Luke 20:5 But they thought within themselves, saying: If we shall say, From heaven: he will say: Why then did you not believe in him?

John 3:18 He that believeth in him is not judged. But he that doth not believe is already judged: because he believeth not in the name of the only begotten Son of God.

John 5:33-36,44-47 You sent to John: and he gave testimony to the truth. . . .

John 10:25,26 Jesus answered them: I speak to you, and you believe not: the works that I do in the name of my Father, they give testimony of me. . . .

John 12:37-43 And whereas he had done so many miracles before them, they believed not in him: . . .

1 John 3:20 For if our heart reprehend us, God is greater than our heart and knoweth all things.